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Full text of "The Flow Of Gases In Furnaces"

DESIGN OF OPEN-HEARTH FURNACES

197

large jets of air and gas from the ports must be given time to mix.
With too short a furnace the flame will extend beyond the hearth.
With too long a furnace the gases of combustion will tend to drop
below the bath temperature.

There are three limitations on the width of the furnace:

1.  The distance material can be thrown through the door by
expert manipulation of a shovel or a dolomite gun.

2.  The width the flame can be spread.

3.  The limitation due to the strength of the roof.

The first controls patching and making bottom. Furnaces
have been built to 16.75 ft wide. This is rather close to the limit.

Table 2 gives the hearth dimensions of a number of furnaces
in service. It shows a considerable diversity in the ideas regarding
this portion of the furnace. Table 3 gives the minimum and
maximum values from Table 2.

TABLE 1

HEARTH AREA OP OPEN-HEARTH FURNACES FOR VARIOUS DEPTHS OF MOLTEN

METAL


	
	Depth of Bath of Molten Metal, In.
								
Capacity
	Cu Ft of
	
								
		
	
	
	
	
	i
		
	

of Furnace,
 TV\T1C!
	Molten Metal
	12
	15
	18
	21
	24
	27
	30
	33
	36

JL ons
	
	(Hearth area in square feet)
								
15
	78.45
	235
	188
	157
	135
	118
	
	
	
	

20
	104 . 60
	314
	252
	212
	180
	157
	139
	
	
	

25
	130.75
	392
	314
	262
	225
	196
	174
	
	
	

30
	156.90
	471
	376
	314
	270
	235
	209
	189
	
	

35
	183.05
	549
	440
	356
	316
	275
	244
	220
	201
	

40
	209 . 20
	628
	504
	420
	360
	314
	278
	256
	229
	209

50
	261 . 50
	785
	629
	525
	450
	392
	350
	325
	286
	262

60
	313.80
	941
	755
	629
	542
	471
	418
	377
	343
	314

75
	392.25
	1177
	940
	785
	674
	588
	523
	470
	429
	392

90
	470.70
	1412
	1130
	945
	812
	706
	628
	567
	515
	471

100
	523.00
	1569
	1255
	1050
	900
	785
	697
	629
	573
	523

Allow from 3 to 6 in for cinder and boil.

y

Formula:   3 ~A.    In which
d

volume of molten metal in charge;

d = depth of bath ; metal only ; A = area of hearth required.   Weight of molten
metal, 430 Ib per cubic foot; 5.23 cu ft per ton.